Shock strut



March 2, 1948.

F. E. BACHMAN' snocx STRUT Filed Aug. 5, i944 INVENTOR. (fi'vzcl/ (5.

Patented Mar. 2, 1948 SHOCK STRUT Fred E. Bachman, Chicago, Ill., assignor to American Steel Foundries, Chicago, 11]., a corporation of New Jersey Application e 9 Serial No. 548,155

17 Claims. 1

' craft and more particularly to'landing gear used between the fuselage or wing-and wheel of an airplane.

The general object of my invention is to provide novel landing gear for aircraft inwhich a shock absorber is employedfor dampingcompression and extension of the gear during landing and taxiing of the airplane.

A specific object'of my invention is to provide landing gear between the'f uselage and wheel of an airplane comprising a lever arrangement connecting the strut and wheel and having associated therewith a shock absorbing device controlling movement between the strut'and the wheel whereby impacts on landing and taxiing of the airplane will be absorbed by the device.

In the drawing, 7

Figure 1 is a side elevation of the landing gear.

Figure 2 is an end elevation as seen from the left of Figure 1. I I

Describing my invention in detail, my novel landing gear comprises a strut generally designated 2, having a tubular body 4 receiving at its upper end a cylindrical portion 6 having a shoulder III in abutment with the end face of the body 4 and being secured to the body 4 by rivets I2 and I4, said portion being provided with a bracket or hinge I6 for connection of the strut in conventional manner to the fuselage of an airplane (not shown). I

Intermediate the ends of the body '4 and surrounding the same is a bracket I8 secured thereto by welding as at 20, said bracket being hinged in conventional manner to the landing gear retracting mechanism (not shown). Received within the lower end of the body 4 is the cylindrical portion 24 having a shoulder 26 in abutinent with the end face of the body 4, and secured thereto by rivets 28 and 30, said portion being provided with a bracket or hinge 32 for pivotally connecting the strut '2 to a shock absorbing device generally designated 34, and also provided with an opening 36 extending therethrough between bosses 38 and 40 formed respectively on opposite sides of the portion 24.

The strut adjacent its lower end extends between a pair of levers or torque arms 42 and 44 and is connected thereto by a hinge pin 46 passing through aligned openings 48 and 50 or the levers and the opening 36 in the strut, the openings 48 and 50 being bushed at 52, 52, respectively, and the opening 36 being bushed at 54. The pin 46 has a washer 56 on one end thereof lbetween the lever 44 and a nut 58,'said nut urging the'inner surfaces of the levers into hearing engagement with the bosses 38 and 40, respectively, and being held inr'place by a cotter pin 60. I l

The levers 42 and 44- are offset as at '62, 62"t0 accommodate the cylinder 63 of the shock absorber therebetween and are curved downwardly for receiving the axle 64 in aligned openings 66, 66 in the ends. thereof, said openings being bushed at 68, 68, respectively. The axle 64 is connected at one side thereof to the wheel diagrammatically indicated at 10 in conventional manner, a collar I2 being fixed to the axle between the brake flange l4 and the lever 44 and held in tight engagement therewith by a lock washer l6 and nut 18 on the opposite end of the axle, said washer having abutment with the lever 42 and the nut 18 threaded on the axle. A suitable cotter pin Bil-may be provided for pre- 35 venting unwanted rotation of the nut. The axle is thus fixed against lateral displacement relative to the levers 42and 44 and rotation of the axle-is also prevented by nut and bolt assemblies 82, 82 extending through complementary openings in the axle '64 and the respective ends of the levers 42 and 44.

The shock absorbing device 34 has its plunger 84 pivotally connected to the bracket 32 of the strut 2 by providing the end of the plunger with an opening 86 in alignment with the openings 88, 88 of the strut bracket 32 for receiving a pivot pin 90, said openings 88, 88 being bushed at 92, 92, and said opening 86 being bushed at 94. The pin is held against displacement by a nut 86 fixed thereon by a lock washer 98 and cotter pin I00.

The cylinder 63 ofthe shock absorber is held in place between the levers 42 and 44 by an annular trunnion band I02 surrounding the same and welded thereto as at I04, I04, said band having bushed. .trunnions I06 and I08, respectively, received in slots H0 and H2 in the inner surfaces of the levers 42 and 44. A bolt II4 may be inserted maligned openings formed transversely of the slot in each lever for pre- 3 Venting displacement of the trunnions in the slots.

In the embodiment of the invention now preferred, the shock absorbing device is of the tension type which, while damping relative movement of the plunger 84 and cylinder 63, by fluid To illustrate the operation of the landing gear, 1

landing of the aircraft will cause impact of the wheel 10 with the ground with resultant movement of the wheel and the associated levers in an upward direction about the pivot 46 of the strut 2. Due to the connection of the brackets and retracting gear mechanism, respectively, the

strut will remainflxed and the wheel and'l'e vers will move relative thereto in a counterclockwise direction (Figure 1). Accordingly, the pin 93 will form the pivot point for the plunger 84 and the associated cylinder 63 will be moved outwardly of the plunger to absorb the shock of the impact, the cylinder rotating on the trunnions I06 and I08 and moving upwardly with the levers and wheel. On rebound of the wheel, the levers and the shock absorber will be moved with the wheel in an opposite direction to absorb the following impact of the wheel with the ground or to assume a normal static position.

In taxiing of the airplane and when the wheel strikes or rides over a projection, the fuselage of the airplane will tend to follow its original level course with the result that the Wheel will be raised and the levers andshock absorber will be moved in a manner similar to that encountered in the landing of the airplane, the movement of the plunger relative to the cylinder damping impact andrebound of the wheel with the round until the same are restored to their initial relative positions under load. Whenthe wheel falls into a depression, the fuselage of the airplane will also tend to follow its original course and the lowering of the wheel into the depression, due to the action of the shock absorber, will cause the levers and shock absorber to be moved in a clockwise direction (Figure 1) and then in an opposite direction upon raising of the wheel by the edge of the depression, both directional'movements effecting a dampening action by the relative contraction and expansion of the shock absorber until the resilient means thereof recovers its normal static load condition.

It may be noted that, by mounting the shock absorber device in the manner described above, the device will obviously respond to horizontal loads as well as vertical loads and the more frequent loads therebetween which are resultants of the vertical and horizontal or drag loads.

vFurther, it is apparent that an additional advantage of my novel landing gear isithe caster effect, in which the wheel is trailing by virtue of the lever connection to the strut, This trailing action tends to maintain the wheels in proper position in relation to the direction of the airplane making it possible to reduce strength of members resisting instability such as may be encountered by aircraft landing gear with less 4 caster effect in negotiating rough terrain with consequent increased tendency to revolve the wheel about the center line of the strut.

An additional advantage is the manner in which the shock absorber device is mounted in this levered arrangement, whereby it is subject to axial loads only, regardless of the forces acting on the wheel, making for economy in construction of the shock absorbing device.

A further advantage is the ease with which replacement of the shock absorbing device can be made, that is, without removal of the wheel or main strut.

It is to be understood that I do not wish to be limited by the exact embodiment of the device shown which is merely by way of illustration and not limitation as various and other forms of the device will, of course, be apparent to those skilled I I in the art without departing from the spirit of I6 and ll! of the strut to the aircraft fuselage the invention or the scope of the claims.

I claim: I. .In alanding gear for aircraft, the combination of a strut having one end adapted for connection to the aircraft, a wheel, a pair of spaced parallel levers extending between said strut and said wheel and pivotally connected to said'strut adjacent the other end thereof and to said'wheel, a shock absorber devic comprising two relatively movable members and means for yieldinglyresisting movement .therebetween, one of said members being positioned. between said:levers and the other of said members being pivotally connected to said second-mentioned end of said strut below the pivotal connection of said levers to said strut, and trunnion means ior pivotally connecting said one member between and intermediate the ends of said levers to said levers.

2. In a landing gear for aircraft, the combination of a strut adapted for connection to the aircraft, a wheel, a pair of spaced parallel levers having opposite ends thereof pivotally connected to said strut and said wheel, said levers providing trunnion bearings between the opposite ends thereof, a shock absorber device between said levers and pivotally connected at one end thereof to said strut, and a trunnion band'surrounding said device and having trunnions received in said trunnion bearings.

3. In a landing gear for aircraft, the combination of a strut adapted for connection to the aircraft, an axle with a wheel mounted thereon, a pair of spaced substantially parallel torque arms pivotally connected at opposite ends thereof to said strut and said axle,.and.an extensible shock absorbing device pivotally connected to said strut and supported above the horizontal center line of said wheel in trunnions in said torque arms, said device being arranged with respect to said arms and strut that compression of said landing gear effects the extension of said device.

4. In a landing gear for. aircraft, the combination of a strut adapted for connection to the aircraft, a wheel, a lever pivotally connected at opposite ends thereof to said strut and said wheel, a shock absorbing device pivotally connected to said lever and said strut, the pivotal connections of said device and said lever to said strut being disposed in the plane of said strut'and so arranged as to cause relative pivotal movement of the device andsaid lever. in opposite directions about their pivotal connection. to each other during extension and compression of the gear.

5. In a landinglgear for aircraft, the combination of a strut adapted for connection to the aircraft, an axle with a wheel mounted thereon,

a pair ofsubstantially --parallel torque arms on one. side of said wheel and pivotally connected atopposite ends thereof to said axle and to said tion of a stru't adapted for" connection to the aircraft, a wheel, a pair of substantially parallel levers extending between said strut and said wheel;each of said levers having one end thereof pivotally connected to-said strut above the lower end thereof and the other end pivotally connected to said wheel at the axis thereof, and a shock absorber device between said levers and pivotally connected thereto intermediate opposite ends thereof and to said strut at the lower end thereof.

7. In a landing gear for aircraft, the combination of a strut adapted for connection to the aircraft, a wheel, a lever pivotally connected to said strut and said wheel, and a shock absorber device comprising two relatively movable members and means for yieldingly resisting movement therebetween, one of said members being pivotally connected to said lever between the ends thereof and the other of said members being pivotally connected to said strut below the pivotal connection of said lever to said strut.

8. In a landing gear for aircraft, the combination of a strut adapted for connection to the aircraft, a wheel, a pair of torque arms pivotally connected to said strut and said wheel, a shock absorbing device comprising two relatively movable members and means for yieldingly resisting movement therebetween, one of said members being pivotally connected to said strut, and trunnion means for pivotallyconnecting the other of said members to said arms intermediate the pivotal connections thereof to said strut and wheel.

9. In a landing gear for aircraft, the combination of a strut adapted for connection to the aircraft, a wheel, a pair of spaced levers pivotally connected at opposite ends thereof to said strut and said Wheel, a shock absorbing device between said'levers, trunnion means pivotally connecting said device to said levers intermediate the pivotal connections thereof to said strut and wheel, and a pivotal connection between said device and said strut at the lower end of the latter.

10. In a landing gear for aircraft, the combination of a strut adapted for connection to the aircraft, an axle with a wheel mounted thereon, a pair of spaced torque arms pivotally connected to said strut and said axle at one side of said wheel, and an extensible shock absorbing device pivotally connected to said strut at the lower end thereof and supported above the horizontal center line of said wheel in trunnions in said torque arms intermediate the pivotal connections thereof to said strut and said axle.

11. In a landing gear for aircraft, the combination of a wheel and axle assembly, a strut adapted for connection to the aircraft, a pair of spaced parallel levers pivotally connected at opposite ends thereof to said assembly and said strut, and a shock absorbing device between said levers and having a pivotal connection at one end thereof to said strut beneath the connection thereof to said levers, and trunnion means pivotally connecting said device to said levers, the pivotal connections of said device and levers to each other and to said strut beingarranged to cause extension of said. device upon compression of said gear..

. 12.v In sending gear for aircraft, the combination of a strut adapted for connection to the aircraft, a wheeLa pair of spaced levers having opposite ends pivotally connected to said strut and said wheel, a shock absorber device pivotally connectedbetween said levers adjacent their connections to said wheel, and a pivotal connection between said shockabsorber and said strut the pivotal connections of said device and levers to each other and to said strut being arranged to cause extension of said'device upon compression of said, ge r-1;

13. In a landing gear for aircraft, the combination of a downwardly extending strut having the upper end adapted for connection to the aircraft, an axle with a wheel mounted thereon, a pair of substantially parallel levers pivotally connected at respective corresponding ends thereof to said strut adjacent the lower end thereof and to said axle, a shock-absorber extending transversely of said levers and comprising two relatively movable members and means for yieldingly resisting movement therebetween, one of said members being pivotally connected to the lower end of said strut below the pivotal connection of said levers to said strut and the other member being disposed between said levers and pivotally connected thereto between the opposite ends thereof and adjacent the pivotal connection of said levers to said axle.

14. In a. landing gear for aircraft, the combination of a strut having its upper end adapted for connection to the aircraft, a wheel, a pair of levers pivotally connected to said strut adjacent the lower end thereof and to said wheel at the axis thereof, and a shock absorber device pivotally connected to said strut at the lower end thereof below the pivotal connections of said levers to said strut and to said levers between the ends thereof.

15. In a landing gear for aircraft, the combination of a strut adapted for connection to the aircraft, a wheel, a pair of l v r p lly connected to said wheel and to said strut, and a shock absorber device between said levers and pivotally connected thereto and to said strut at the extremity thereof and below the pivotal connections of said levers to said strut.

16. In a landing gear for aircraft, the combination of a downwardly extending strut having the upper end adapted for connection to the aircraft, an axle having a. wheel mounted thereon, a pair of substantially parallel levers having trunnion means between opposite ends thereof and having respective corresponding ends connected to said strut adjacent the lower end thereof and to said axle, a shock absorber device between said levers intermediate opposite ends thereof and extending transversely of said levers and being pivotally connected at one end thereof to the lower end of said strut and adjacent the other end thereof to said trunnion means whereby compression of said gear causes extension of said device.

17. In a landing gear for aircraft, the combination of a downwardly extending strut adapted for connection to the aircraft, an axle having a wheel mounted thereon, a lever having the opposite ends thereof pivotally connected respectively to said strut adjacent the lower end thereof and to said axle, a shock absorber device extending transversely of said lever and pivotally connected thereto intermediate opposite ends thereof and pivotaliy connected'at one end thereof to the lower end of said strut, the pivotal connections of said device and said lever to said strut being so arranged as to cause relative piv- 5 otal movement of the device andsaid lever in 0D- posite directions about their pivotal connections to each other to effect extension of said device during compression of saidgear. 10

FRED E. BACHMAN.

REFERENCES CITED The following references are of record in the 15 file of this patent:

- Number UNITED STATES PATENTS Number Name Date Wyckofi' Jan, 20, 1914 Vintila Nov. 2, 1915 Shankland July 19, 1921 Gordy July 28, 1931 Pearse Dec. 31, 1935 Dowty Sept. 26, 1939 Dowty May 18, 1943 'Focht Nov. 21, 1944 FOREIGN PATENTS Country Date Sweden Jan. 17, 1918 Great Britain --Oct. 2, 1940 Great Britain Jan. 28, 1942 

